#include <cstdlib>
#include <iostream>
using namespace std;

void f(int level, int throw_level)
{
    if( level == throw_level){
        throw level;
    }
    else{
        f(level+1, throw_level);
    }
}
int main(int argc, char* argv[])
{
    try{
        int throw_level = argc > 2 ? 0:atoi(argv[1]);
        if( throw_level == 0){
            throw 0;
        }
        else{
            f(1, throw_level);
        }
    }
    catch(int e){
        cout << e << endl;
    }
}
